Package for fluent materials with a propellant operated gel piston



Feb. 8, 1966 G. DE WAYNE MILES 3,233,791

PACKAGE FOR FLUENT MATERIALS WITH A PROPELLANT OPERATED GEL PISTON Filed July 9, 1963 INVENTOR GILBERT De WAYNE MILES United States Patent F 3,233,791 PACKAGE FOR FLUENT MATERIALS WITH A PROPELLANT OPERATED GEL PISTON,

Gilbert De Wayne Miles, Ossining, N.Y., assignor to Colgate-Palmolive Company, New York, N.Y., a corporation of Delaware Filed July 9, 1963, Ser. No. 293,723 17 Claims. ((31. 222-389) This invention relates to a package and process for dispensing fluent material therefrom. .More particularly, the invention relates to a multi-compartmented container, a piston therefor, and processes associated therewith.

The use of pressurized dispensing containers for a large variety of products has become widely accepted in many fields, including the dispensing of non-expanded products such as tooth pastes, and of expanded foams and lather such as shaving preparations and the like. One-compartment containers, in which products to be dispensed and propellants therefor are associated, have proven to be unsatisfactory for a number of products since initial portions of the products are generally dispensed with an excess of propellant, and final portions remaining in the container are deficient in propellant. It has been necessary generally to charge an excess of such foamant in order to have sufiicient foarnant for discharge of a substantial portion of product in the container. And it is necessary as the container is used to discharge intermediate portions of product therefrom, to shake the container so as to reemulsify product and foamant. Consequently, many users do not or can not exhaust the entire product supply in the container, but on the contrary, dispose of the container when it has been only partially exhausted of product. Quite naturally, this has been the reason for some consumer dissatisfaction.

In an effort to overcome the disadvantages of the foregoing character, several modifications have been made of early aerosol containers for dispensing fluent products. One-compartment containers have given way to twocompartment containers for many products. In the latter containers, product is contained in a first compartment or section defined by a valve or outlet means and by a piston, bag or diaphragm which keeps the product separate from a second compartment or section in which a propellant is located. Product is delivered from the container in natural state, since no propellant or foamant is present in the first section.

It has been proposed to use a flexible bag to serve as a first section, with product and an inert gas therein in order to deliver product in an expanded state. Freon is used as a propellant in a second section and exerts pressure upon the flexible bag. While this proposal might overcome some disadvantages of earlier one-compartment containers, it suffers from certain practical shortcomings. The flexible bag must be thin walled such that it will collapse as product is expelled therefrom. However, as collapsing quality is realized, permeability of the bag to gases increases giving rise to dilution of product in the bag by Freon entering the bag and by change of composition of the bag contents by inert gas flowing from the bag to the Freon section. Additionally, if the bag has a weak area, it will collapse at that area as product is expelled and remaining product will be isolated or pinched off, thereby making impossible complete exhaustion of product in the bag. Other difiiculties with a bag for containing product in a two-compartment dispenser include expense of installation and filling of the bag with product.

Two-compartment pressurized containers with pistons serving to separate the compartments, while generally advantageous, have several shortcomings. For example plastic, metal and rubber pistons used therein must be shaped prior to being inserted in a container body. Since 3,233,791 Patented Feb. 8, 1966 the inside diameter of the body varies within certain tolerances and since the largest diameter of the pistons also varies Within similar tolerances, conformation of piston with container body is not uniform. Some pistons fit too tightly in the container body and require considerable propellant pressure to move them toward the discharge valve or outlet means of the container. Other pistons fit so loosely in the container that an ineffective seal is formed between the piston and container walls such that propellant enters the product section and dilutes product therein; additionally, product flows down through the annulus formed by the container and piston walls and is lost in the propellant section.

Accordingly, a need exists for more advantageous and efiicient packages and dispensing processes in order to avoid or lessen deficiences such as those mentioned above.

It is an object of this invention, therefore, to provide a multi-compartment package for dispensing fluent product therefrom. Another object is to provide a package which can be completely exhausted of fluent product. A further object is to provide a package for dispensing fluent product in an expanded state. Still another object is to provide a multi-compartment package'wherein a product compartment and a propellant compartment are separated by a slidable piston comprised of a gel. Another object is the provision of such a package wherein product and propellant remain emulsified and of substantially constant' composition, and wherein losses of product and propellant are minimized. And another object is to provide a process for dispensing fluent product from such a package. Still another object is to provide a piston comprised of a gel. A further object is the provision for forming a gel piston in place in a container. Still other objects will appear from the following description.

The foregoing objects are realized with the present invention. Although the package, piston and processes described and claimed herein are readily adaptable to a wide variety of applications, the invention is particularly useful for dispensing dental cream and for dispensing shaving lather; and, for convenience at this part of the application, details are given in connection with such products. As explained hereinafter, however, it is to be understood that the present invention can be employed with a wide range of products.

The invention is described now with reference to the accompanying drawings in which:

FIGURE 1 is a verticalsectional view in elevation of a preferred embodiment of a pressurized container of dental cream or shaving lather inaccordance with the invention;

FIGURE 2 is a disassembled view of the elements of such container;

FIGURE 3 is a vertical sectional view in elevation of another embodimentof the invention wherein a modified piston is employed; and

FIGURE 4 is a plan view of -a container according to the invention.

Referring more specifically to the drawings, numeral 11 generally designate-s a dispensing container having a tubular body 12 and a top opening defined by a rim 13 adapted to have a normally close-d dispensing valve 15 sealed thereto. The valve 15 can be staked directly to the container or can, as illustrated, be fastened to a valve fitment 16 which is staked, or rolled into pressure tight engagement with the container at rim 13. Gaskets (not shown) between 11, valve 15 and fitment 16 are utilized to assure pressure tight joints.

Valve stem 17 is fitted with a spout 18 and a button 19. When button 19,'is manually depressed, it forces the valve 15 to open and permit dispensible material to be expelled through the valve stem 17 and out through the spout 18. A closure member 20 is staked and rolled into pressure tight engagement with the tubular body 12 at the end opposite valve 15.

Inside the container 11 and separating the interior into a first section 21, at one end of which valve 15 is located, and a second section 22, opposite thereto, is a slidable piston 23' comprising a gel. This is described in detail hereinafter. The first section 21 is filled with dental cream, or with a shaving preparation having dispersed therein a propellant or foamant capable of expanding upon release to the atmosphere and causing the shaving cream to foam.

A second section 22 of container 11 is filled with propellant which is described hereinbelow. The propellant used is one capable of maintaining a substantially constant pressure in the package from manufacture or assembly until product has been exhausted therefrom. Moreover, the vapor pressure in the propellant section 22 of container 11 is at least slightly greater than the vapor pressure, if any, in the product section 21 such that slidable piston 23 is urged toward valve 15. Because of the particular character of the piston used herein, the pressure differential of propellant section 22 over product section 21 need only be sufficient to move the slidable piston 23 toward valve 15 and can be as small as about 0.2 pound per square inch. It will be recognized that while such a vapor pressure differential is employed with dental creams or shaving preparations, greater or lesser vapor pressure differentials will be used dependent upon the character, as viscosity, of other dispensible products such as catsup, mustard, etc.; the relative fit of slidable piston 23 with the side wall of container 11, etc.

The slidable piston 23 referred to hereinabove, dividing container 11 into sections 21 and 22 is composed of a relatively flexible gel which is substantially inert to the dispensible product, propellant and other materials making up the package. The gel is organic in chemical composition, and is represented by gels of natural gums such as agar, tragacanth, etc., synthetic gums, gelatin, etc. Particularly preferred herein, however, is agar (a polysacoharide).

One important feature of the gel pistons of this invention is their capacity to be formed in place in a container (such as 11). A suitable solution of a gel-forming organic material, typified by a 1 percent aqueous agar solution, can be poured into container 11, and allowed to harden into a cylinder indicated as piston 23. The agar solution spreads out in container 11 and hardens, the circumference thereof conforming closely to the lateral wall .of body 12. In this way a tight fit of piston 23 and body wall is obtained. Thus, the need for tolerances of piston and body diameter of metal, plastic or other materials used to date, does not arise. Piston 23, therefore, forms a fluid (liquid and gas) tight seal with the body wall. Despite damage of container 11 in transit or storage, as by denting of the body 12, gel piston 23 is sufiiciently flexible that it accommodates to the damage and, as mentioned hereinabove, but little pressure differential is required to force it toward the valve 15 of the container.

Since piston 23 conforms closely to the lateral wall of body 12 and a fluid-tight seal is maintained, leakage of product or product and propellant in section 21 into section 22 is substantially eliminated. So, too, is leakage of propellant in section 22 into section 21. Thus, a dispensible product of uniform concentration can be made available in section 21 when that section is charged with product and as that product is discharged therefrom through to exhaustion of product from section 21. Also, when product and propellant are charged to section 21 so as to be delivered as a foam, the foam initially delivered through spout 18 and the foam later delivered are of substantially constant composition. In such case, propellant in section 21 is emulsified or dissolved in the product therein and remains so; there is, then, no need to shake container 11 to bring about reemulsification of propellant and product charged together to section 21.

Stable emulsions or solutions are made available rather than charging an excess of propellant to section 21.

A preferred modification of slidable piston 23 is reinforcement of a gel with a reinforcing agent, particularly a fibrous reinforcing agent. The latter can comprise asbestos fibers, glass fibers, cotton floc, paper pulp, wood fibers and shavings, plastic filaments such as nylon filaments, metal wool such as steel wool and aluminum wool, etc. Such reinforcing agents are substantially inert to product, propellant and materials comprising a package. Advantages of such reinforced gel pistons include the feature of forming them in place in a container. For example, a gel-forming solution can be poured into container 11, with reinforcing agent therein, and agitated in the container so that the agent is well distributed; the resulting mixture can then be allowed to set into a gel. If gel-forming solution is added without the agent, the latter can then be added thereto in container 11, and the two can be agitated as mentioned and allowed to gel. Reinforced gel pistons are advantageous because of their physical strength.

Another desirable modification of slidable piston 23 involves use of a piston comprising a gel and a substantially completely communicating cellular structure. Such a piston is illustrated with member 25 which can be a foam of a synthetic resinous material such as polyurethane or other foamable and preferably resilient plastic, associated with a gel. Cellulose foams, natural sponge, and like materials are also contemplated herein for use with a gel. In such pistons, the foam serves as a matrix for a gel. By way of illustration, an aqueous agar solution can be added to container 11, followed 'by an opencell polyurethane foam 25 preferably having a diameter larger than and approximating the inner diameter of the container. The solution fills at least a portion of the multiplicity of small voids 26 of foam 25, thereby forming a slidable piston. A small amount of a soap or surfactant can be included in the agar solution, or like solution, to aid in displacing air present in the open-cell foam. Particular advantages of such a piston include: a persistent elastic memory of the foam to conform with the container wall, and conformance with the container wall with change of conditions such as temperature and pressure.

Still other modifications of gel pistons are contemplated herein. A gel piston can be formed in a container or inserted therein, a layer of impermeable material such as aluminum foil can be placed thereon, and another layer of gel can be formed on the aluminum foil. Such sandwich pistons are advantageous for reducing permeability to a minimum. It will be understood that layers of an impermeable material, such as aluminum, can embrace a layer of gel; or that a piston can comprise a gel, the upper or under surface of which is covered with an impermeable material. While aluminum foil has been used by way of illustration, other typical substantially impermeable materials include polyethylene, polypropylene, vinyls, waxes, etc.

Since the slidable gel pistons used herein are relatively flexible, whether reinforced or not, they can deform without shearing and conform to the base 24 of valve 15 as they come into contact therewith and with the lateral wall of body 12 proximate thereto. Thus, as the slidable piston 23 or 25 is urged toward valve 15 and the base thereof 24, the piston deforms and substantially all of the product in section 21 is forced out of container 11.

As a guide, and not by way of limitation, the ratio of the vertical dimension of the piston 23 against the wall of the container 11 to the diameter thereof is from 1:1 to about 1:2.

Referring now to propellants which can be used in product section 21 as propellants or foaming agents, these include inert gases such as carbon dioxide, nitrogen, nitrous oxide, etc. and liquified gaseous materials such as aliphatic hydrocarbons, partially iluorinated and partially or wholly chlorofluorinated hydrocarbons. Hydrocarbons are pref erably saturated and are such as propane, n-butane, isobutane and cyclobutane. Fluorinated and fiuorochlorinated compounds are represented by: 1,1-difluoroethane; 1,2-dichloro 1,1,2,2 tetrafluoroethane; trichlorotrifluoroethane; dichlorodifluoromethane; monochlorodifluoromethane; monofluoromonochloromethane; and l-monofluoro-Ll-difiuoroethane. One or a mixture of such compounds can be used. Generally, selection of a foamant or propellant for section 21 will depend upon the character of the product associated therewith, for example whether it is edible or non-edible, whether to be in contact with animals, viscosity of the product, chemical character of the product, etc.

With shaving preparations to be dispensed as foams, it is preferred that saturated hydrocarbons be used, since they perform a lather-forming function without undesirable burning of human skin. With shaving preparations, one or a mixture of compounds as those mentioned having a vapor pressure ranging from about 20 to about 60 p.s.i.g., preferably 40 to 50 p.s.i.g., at about 70 F., can be used. Homologs of the foregoing compounds having vapor pressures outside of the stated ranges can also be used, so long as the combined vapor pressure is within the stated ranges.

When-dental creams are to be dispensed as foams from section 21, it is preferred to use CO or Freons such as dichlorodifiuoromethane and 1,2 dichloro 1,-1,2,2 tetrafluoroethane as foamants. correspondingly, a whipped cream is dispensed with an inert gas such as nitrogen, carbon dioxide or nitrous oxide serving as the foamant in section 21.

The quantity of propellant or foamant used in product section 21 of container 11, can vary considerably with the character and type of dispensible product. With shaving preparations, generally from about 1 to about 5 parts by weight of foamant is used for 100 parts by weight of product. Such quantities provide excellent dispersions which, when dispensed from container 11, are desirable foamed products. And such quantities are sufiicient to remove product in expanded state, e.g. a foam, from container 11. Stable emulsions within product section and foams of desired density from spout 18, are provided by using such quantities.

Propellants useful herein in section 22 include those mentioned above as suitable for use in section 21. Many exist in the form of a gas at ordinary temperatures and pressures. They can liquify at lower temperatures or when under pressure in a container such as those described and claimed herein. Generally, the propellants have vapor pressures ranging from about 20 to about 160 p.s.i.g., preferably 40 to 70 p.s.i.g., at 70 F. Either a simple compound or a mixture of two or more of such compounds can be used. And other homologs individually having vapor pressures outside of the desired ranges set forth, can be used with other homologs, if the combined vapor pressure falls within such desired ranges. By way of illustration, kerosines and light mineral oils can be utilized.

Regardless of which of the particular compounds or mixtures thereof are employed herein as propellants, it is not necessary to be concerned about the eliect of the propellant on the physical or chemical properties of the dispensible product or their effect upon a surface or area to which the product is applied. This follows from the facts that the propellant or propellants are substantially completely isolated in the propellant section 22 of container 11 and that they do not come into contact with the product to be dispensed. Accordingly, in a pressurized package or container of a shaving preparation manufactured in keeping with this invention, those compounds set forth above as propellants which cause a tingling sensation to the skin or instability of lather can be employed since they are completely isolated from the dispensible product in section 21.

As indicated above, the vapor pressure of propellant in section 22 will depend upon the force necessary to urge slidable pistons such -as,23 and 25 toward the valve end of container 11.

It is to be understood that container body 12 can be composed of a wide variety of materials including steel, aluminum, plastics such as polyolefins. Valvesas 15- used herein are those conventionally used; however, they need not have in combination therewith a dip tube.

The base or closure member 20 can have a filling plug or a spot weld therein (neither shown), such plug or weld serving as a safety member to avoid explosion under unusual circumstance. The plug, for evample, can be composed of natural or synthetic rubber, and can be one having a self-sealing filling channel (not shown).

It will be recognized that containers can be assembled from the several parts described above and charged with products, liquified gaseous materials and propellants so described, in a variety of manners. A particularly advan-- tageous assembling operation is as follows. Container 11 having a closure member 20 secured to body 12 and having a capacity of six (6) ounces, is used. An aqueous agar solution is poured into a container to a depth of about 1% inches, the container having an overall height of approximately 4 /2 inches. Asbestos fibers (about 10 percent by weight, based upon the agar solution) are then added and stirred into the agar solution in order to disperse them throughout the solution. The resulting mixture is allowed to gel. Shaving preparation is then added to section 21 of container 11 so that little space remains at the top of this section. Valve 15 is then inserted at the top of body 12 and is crimped thereto. Propellant, such as a hydrocarbon mixture and indicated by 28, is then charged to section 22 of container 11; this is charged through a hole (not shown) in closure member 20 and the hole is then plugged with a rubber plug (not shown).

' Liquified gaseous material-a mixture of propane (13%) and isobutane (87% )-is charged as a gas through valve 15. When so charged product section 21 is substantially filled, there being no head space therein.

Illustrative of the containers of this invention is an excellent dispenser for shaving lather containing about 5.5 ounces (avoirdupois) of product and having a capacity when empty of 7 fluid ounces:

Product: Grams Soap solution C -iC mixture 1 1 Propellant:

C -iC mixture 0.5

Slidablepiston: Asbestos-reinforced agar gel.

Vapor pressure of product section 21 of this container is about 60 p.s.i.g. at 70 F., and that of propellant section 22 is about 65 p.s.i.g. at 70 F.

r A container equipped with a slidable piston of an agar gel associated with an open-cell polymethane foam 25 can be readily assembled according to the following procedure. With a container 11 of six (6) ounces capacity and having closure member 20 secured to body 12, aqueous agar solution is added thereto to a depth of about 1% inches. An open-cell polyurethane foam 25 having a diameter slightly in excess of that of container body 12 is inserted into the container and is forced to the bottom of the container and into the agar solution. The solution enters and occupies voids 26 of foam 25 and, on standing, gels. Shaving preparation is added to section 21 of container 11; little space remains empty in this section. Inserted at the top of body 12 is valve 15, which is crimped thereto. Propellant is charged to section 22 of container 11, as explained above. Foamant is charged to section 21 as a gas through valve 15, such that there is substantially no head space therein.

In addition to shaving compositions and dental creams illustrated above, a wide variety of fluent products can be dispensed in natural state or in an expanded state in accordance with this invention. Shampoos, hand lotions, face creams, dentifrices and other toilet compositions are contemplated. So, too, are edible products typified by whipped creams, icings, catsup, mustard, mayonnaise, etc. Antiseptics and medicinal ointments can be used. Still other products are paints, lacquers, chemicals, etc.

Numerous modifications and variations of the invention may be made without departing from the spirit and scope thereof. Accordingly, it is to be understood that the invention is not to be limited, but is to be construed in the light of the language of the appended claims.

Ielaim:

1. A package for dispensing a fluent product comprising a first section containing a dispensible product and having outlet means for dispensing said product,

a second section containing propellant under pressure,

and

a slidable piston comprised of a gel for separating said first and second sections one from the other.

2. A package defined by claim 1 wherein the vapor pressure differential between the contents of said first and second sections is at least about 0.2 pound per square inch.

3. A package defined by claim 1 wherein said propellant is a fiuoro chloro aliphatic hydrocarbon.

4. A package defined by claim 1 wherein said product is a dental cream.

5. A package for dispensing a fluent product in an expanded state comprising a first section containing under pressure substantially unexpanded dispensible product having a propellant dispersed therein and having outlet means for dispensing said product to the atmosphere in an expanded state,

a second section containing propellant under pressure,

and

a slidable piston comprised of a gel for separating said first and second sections one from the other.

6. A package defined by claim 5 wherein said slidable piston is comprised'of an agar gel.

7. A package defined by claim 5 wherein said slidable piston is comprised of an association of an agar gel and a reinforcing material.

8. A package defined by claim 5 wherein said slidable piston is comprised of an association of an agar gel and asbestos fibers.

9. A package defined by claim 5 wherein said slidable piston is comprised of an association of an agar gel and an impermeable synthetic resinous cellular foam material.

10. A package defined by claim 5 wherein the vapor pressure differential between the contents of said first and second sections is at least about 0.2 pound per square inch.

11. A package defined by claim 5 wherein said propellant in said second section is a fiuoro chloro aliphatic hydrocarbon.

12. A package defined by claim 5 wherein said product is a shaving cream.

13. A package defined by claim 5 wherein said propellant in said first section is a mixture of propane and isobutane.

14. A package for dispensing a fluent product comprising a first section containing a dispensible product and having outlet means for dispensing said product, a second section containing propellant under pressure, and a slidable piston comprising an agar gel for separating said first and second sections one from the other.

15. A package for dispensing a fluent product comprising a first section containing a dispensible product, and having outlet means for dispensing said product, a second section containing propellant under pressure, and a slidable piston comprising an association of an agar gel and a reinforcing material for separating said first and second sections one from the other.

16. A package for dispensing a fluent product comprising a first section containing a dispensible product and having outlet means for dispensing said product, a second section containing propellant under pressure, and a slidable piston comprising an association of an agar gel and asbestos fibers separating said first and second sections one from the other.

17. A package for dispensing a fluent product comprising a first section containing a dispensible product and having outlet means for dispensing said product, a second section containing propellant under pressure, and a slidable piston comprising an association of an agar gel and an impermeable, synthetic, resinous, cellular foam material separating said first and second sections one from the other.

References Cited by the Examiner UNITED STATES PATENTS 1,977,580 10/1934 Grier 264-140 2,070,167 2/1937 Iddings.

2,447,056 8/ 1948 Cooper.

2,655,480 10/1953 Spitzer et al. 252- 2,684,774 7/ 1954 Aichele.

2,772,194 11/1956 Fisher ct a1 264-271 X 2,799,054 7/1957 Van Rossem 264-225 2,847,148 8/1958 Altseimer 222-389 2,855,632 10/1958 Croce et al. 264-242 X 2,908,650 10/1959 Fine 252-90 3,022,923 2/1962 Hoffman 222-389 X 3,092,555 6/1963 Horn.

3,095,259 6/1963 Smith.

3,112,846 12/1963 Hein 222-389 X 3,117,404 1/1964 Miles 222-389 X 3,117,699 1/1964 Epstein 222-389 RAPHAEL M. LUPO, Primary Examiner. 

1. A PACKAGE FOR DISPENSING A FLUENT PRODUCT COMPRISING A FIRST SECTION CONTAINING A DISPENSIBLE PRODUCE AND HAVING OUTLET MEANS FOR DISPENSING SAID PRODUCT, A SECOND SECTION CONTAINING PROPELLANT UNDER PRESSURE, AND A SLIDABLE PISTON COMPRISED OF A GEL FOR SEPARATING SAID FIRST AND SECOND SECTIONS ONE FROM THE OTHER. 